I recently picked up a gallon of Echo B&C oil at Home Depot after reading good reviews on it. Pretty tacky, and only $12. Haven't used more than 1-2 tanks but I like it more than the crap I got last time I was at Tractor Supply
I used some of my buddy's stock of older orange Stihl last week. From room temperature in the house it is quite thin but at 20 degrees it is too thick so we used the blue jug until temps got into the mid 30's.I have always bought the orange jug and have not seen a difference yet. The weather temp does change it a bit but if it is that cold I stay in.